Assessment and determination of optimum concentration of streptomycin and kanamycin as selective agents in peppermint (Mentha piperita L.) transformation

Antibiotics as selective agents play a remarked role in development of plant transformation technologies. In this research, the effect of streptomycin and kanamycin antibiotics as selective agents was studied. Plant samples were provided from greenhouse and in vitro cultures. The experiments were analyzed in a split plot in time based on completely randomized block design. Moreover, for quantification of the variation due to the effect of the antibiotic on plant samples, chlorophyll a, b and carotenoid were measured. Results of analysis of variance (ANOVA) showed a significant concentration×day interaction at 0.01 level. The concentrations would be caused whiteness of apexes and lateral buds and finally, plant death. Kanamycin concentration of 100 ppm was in shoot and bud samples caused whiteness of apexes and lateral buds during 30 to 45 days and finally plant death. The concentration of 50 ppm over 45 days resulted in death of leaf samples. The concentration of 250 ppm was the optimal dose. Analysis of variance of different concentrations was significant at 0.01 level for photosynthetic characters including chlorophyll a, b, total chlorophyll, chlorophyll ratio a/b and carotenoid. Changes in mean values of these treatments for all the pigments showed a decreasing trend.In conclusion, streptomycin concentration of 250 ppm and kanamycin concentrations of 50-100 ppm were the optimal doses to select non-transformed peppermint tissues. The results of this study revealed that the optimum doses of the antibiotics would had high efficiency in selection of non-transformed peppermint tissues which may be proposed in transformation researches.